Light emitting diode (LED) lighting systems are becoming more prevalent as replacements for existing lighting systems. LEDs are an example of solid state lighting (SSL) and have advantages over traditional lighting solutions such as incandescent and fluorescent lighting because they use less energy, are more durable, operate longer, can be combined in multi-color arrays that can be controlled to deliver virtually any color light, and contain no lead or mercury.
In many applications, one or more LED dies (or chips) are mounted within an LED package or an LED module, which may make up part of a lighting fixture which includes one or more power supplies to power the LEDs. Some lighting fixtures include multiple LED modules. A module or strip of a fixture includes a packaging material with metal leads (to the LED dies from outside circuits), a protective housing, and/or a combination of leads, housing and heat sink.
An LED fixture may be made with a form factor that allows it to replace a standard incandescent fixture or bulb, or any of various types of fluorescent or halogen lamps. LED fixtures and lamps often include some type of optical elements external to the LED modules themselves. Such optical elements may allow for diffusion, localized mixing of colors, collimate light, provide a controlled beam angle and/or provide beam shaping. Optical elements may include reflectors and/or, lenses. Lenses may be of glass or plastic and as examples may take the form of lens plates, total internal reflection (TIR) elements, or more traditional circular, concave or convex lenses.